Generally, a crawler formed of rubber, a metal core and a steel cord is called a caterpillar track which is used as a wheel component in agricultural or industrial machineries such as a combine, a motor-lorry, an excavator and a snowplow.
The crawler enhances operation efficiency on the soft ground and also allows environmentally friendly movement and work. Particularly, the crawler is used as a substitute for a steel chain in an excavator in order to improve noise and vibration, thereby enhancing a comfortable ride.
FIG. 1 is a longitudinal cross-sectional view of a conventional rubber crawler in which a metal core is embedded. Referring to FIG. 1, the crawler 1 includes a lug 2 which is formed to protrude on an external side surface and grounded on the ground; a steel cord 3 as a tension member which is disposed internally for enduring compressive load and driving load of a tracked vehicle and maintaining a sufficient rigidity and tensile strength; and a metal core 5 which is embedded within the steel cord so as to transfer the driving force of an engine while maintaining the shape of the crawler 1.
Herein, since the metal core 5 formed into a single body has not a separate structure for reinforcing the rigidity, the whole rigidity of the crawler 1 is lowered and also the crawler 1 may be easily separated by external shock applied from the side surface, thereby causing wheel separation.
In order to solve the problem, there has been proposed a new structure of the metal core for improving the wheel separation. FIG. 2 is a cross-sectional view of a conventional crawler in which an improved metal core is inserted. Referring to FIG. 2, the crawler includes a lug 12 which is formed to protrude on an external side surface; a steel cord 13 which is disposed therein; and a metal core 15 which is integrally embedded within the steel cord 13.
In the conventional crawler for improving the wheel separation, adjacent metal core extensions 15a and 15b for preventing the wheel separation support each other against the external force generated in the transverse direction of the crawler 11. However, when the external force is simultaneously generated in the up and down direction as well as the transverse direction of the crawler 11, there is a problem that the wheel separation preventing function is not performed smoothly.
Further, in the conventional metal core structure for preventing the wheel separation, as shown in the Y portion of FIG. 2, the metal core extensions 15a and 15b for preventing the wheel separation are not located at the upper side of an insertion portion of the steel cord 13, and the lower portions of the metal core extensions 15a and 15b are located on the bottom surface of the metal core 15.
Furthermore, since the metal core extensions 15a and 15b are not located completely at the internal surface of the lug 12, there is other problem of being weak in the bend fatigue, the metal core exposure due to foreign substances and the breakage of a tread portion.